Dissolution of titaniferous ore concentrates with amine addition



United States Patent- DISSOLUTION 0F TITANIFEROUS ORE CONCEN- TRATES WITH AMINE ADDITION No Drawing. Application July 30, 1953, Serial No. 371,417

9 Claims- (Cl. 23-117) This invention relates to the attack of ores. More specifically, it relates to the attack of titaniferous ores such as ilmenite with concentrated sulfuric acid. This invention also relates to the dissolution in strong sulfuric acid of ore concentrates containing small amounts of flotation agents.

In the preparation of ores and minerals for metallurgical treatment it is common practice to remove gangue and foreign material, and concentrate the desired fraction of the ore by any of numerous known procedures. Among the procedures that have been used may be mentioned magnetic separation, wet and dry classification, and flotation concentration. concentrated by flotation methods that the present invention is particularly concerned.

The flotation agents used in the flotation concentration of ores and minerals are generally surface active organic compounds capable of preferentially wetting a desired fraction of the ore which may be, for example, fatty acids such as stearic or oleic acid, soaps and similar types of compounds, usually in conjunction with petroleum agents, such as fuel oil and the like. These compounds when used in the flotation process are strongly adsorbed on or absorbed by the ore or possibly react with it to some extent so that it is exceedingly diflicult or impossible to remove the last traces of organic flotation agents from the float fraction of the ore by normal washing methods and the like.

When ore concentrates containing residual amounts of such flotation agents are further treated by attacking them with strong sulfuric acid, difliculties in operation are frequently encountered by reason of changes in the It is with ores that have been character of the reaction resulting from the presence of ores, such as ilmenite, to produce titanium solutions useful in the preparation of titanium pigment, for example the digestion or attack of the ilmenite with concentrated sulfuric acid, is ordinarily a vigorous, rapid reaction which may, however, be controlled by using suitable digestion equipment and appropriate techniques, both of which are well known to the art. When the ilmenite contains flotation agents, the vigorous and copious foaming of the reaction frequently renders it uncontrollable and dangerous.

When excessive foaming takes place during the digestion reaction, an appreciable economic loss is sustained because the foaming carries part of the reaction mixture out of the tank altogether, while an additional portion is removed from the heat of the reaction zone and does not react properly, much of the ore remaining entrapped in the foam and unattacked by the acid.

A severely foaming ore, moreover, will actually be extruded from the tank, and the large quantities of steam and gas evolved during the reaction carry entrainedore, acid and reaction products out through the tank stack. The hot, strongly corrosive froth endangerspersonnel and may cause extensive damage to equipment and structural work in the area. Moreover, the violence of the foaming is unpredictable since the precise quantity of residual flotation agent present, and the consequent effects thereof, will vary from batch to batch.

This element of unpredictability renders it diflicult or impossible to so vary the digestion conditions as to offset the effect of the flotation agent present. The di-' gestion reaction must be sufliciently strong and vigorous to supply its own heat requirements and, therefore, the reaction conditions cannot be excessively mild; on the other hand, reaction conditions (acid concentration, acid/ore ratio, initial temperature of reactants etc.) if so adjusted as to promote a normal vigorous reaction, may easily render the reaction altogether uncontrollable when flotation agents are present.

While this invention is here described with particular reference to the dissolution of ilmenite ore in concentrated sulfuric acid, it will be obvious that the invention is equally applicable to other reactive titaniferous ores as well as to any other flotation concentrated ore which reacts exothermically with sulfuric acid.

Although foam-producing agents are most commonly introduced during the ore-dressing operations, by flotation processes, they may also occur in the ore for other reasons. For example, it has been suggested to spray ore piles with fuel oil or asphalt in order to cut down wind losses. These agents, which are similar or identical to the fuel oils used as oily collectors in flotation processes, produce the same troublesome foaming at reaction as do the flotation agents used as such, and the process of the present invention is equally applicable to the prevention of foaming from this cause. Moreover, other but less common sources of contamination by these oily materials, including accidental contamination from fuel supplies or the like will produce the same troublesome foaming and may be effectively treated in the same way. The term flotation agents as used herein should, therefore, be construed to include materials such as asphalt and fuel oil even when not actually used for flotation purposes.

An object of this invention, therefore, is to provide a method for rendering amenable to digestion in concentrated sulfuric acid an ore concentrate containing organic flotation agents. Another object is to provide a method for treating an ore concentrate which will overcome the tendency of residual flotation agents to render foaming at the digestion reaction violent and uncontrollable. A still further object is to provide an economical method for treatment of an ore concentrate containing an organic flotation agent which will make possible a normal digestion procedure with good digestion eificiencies. An additional object is to provide such a method which produces from a titaniferous ore a reaction product suitable for the manufacture of high-grade titanium pigments and thelike. These and other objects will become apparent from the following more complete description of the present invention.

In its broadest aspects, this invention contemplates a method for treating an ore containing organic flotation agents which comprises adding to said ore a small amount of a secondary amine, said amine having the formula:

N RII 7 wherein R and R represent saturated alkyl radicals concompound is added to the ore in appropriate amount,

a"; ..\w a

which is generally between 0.91% and 0.5%, preferably between 0.05% and 9.2% on an ore weight basis, the

tive 'or their effect is offset, so that the reaction proceeds'in a normal, vigorous butbontrollable manner'entirely similar to the type of reaction to be expected from a similar ore not containing residual'flotation agents.

rimary amines of the type HzNR and tertiary amines of the type NR3, while in some cases exhibiting-a degree of controlling action upon the digestion r action, are in general not effective, especially when added in economi-- cally feasible amounts. effective whether added as suchor neutralized with min- Secondary amines (HNRz) are in V .7: 7 A

flotation agents present are apparently rendered ineffecin solid form .to'the orein'the digestion vessel itself, or may be added to or dissolved in the sulfuric acid used for. the attack of the ore. V

The use of larger amounts of treating agent than those above specified is contemplated, but is ordinarily not economically justified. Smaller amounts than those given above are also effective in-some cases in controlling the foaming at reaction, depending upon the amount or re.

sidual flotation agent present. The amounts ofifiotation agents present in 'the ore concentrate. are generally extremely small. Normally, from one to five pounds of the flotation agents are employed per. ton of ore in flotation methods. The amount. present in the. ore concentrate is ordinarily somewhat jlowerl than the amount initially emintendedhere and throughout the Specification and claims to include simple secondary amines of the type 7 V V V /NH V R V and also dialkylarnides of fatty acids, which may 'be represented by the formula 1 a a R V where R and R are defined as above and ii r (tir i is theacyl group of 'a saturated organicracid containing up to 20 carbon atoms, secondary ammonium salts of the 7 type where X is' the anion of a mineral or saturated organic *acid, and acyldialkylammonium salts of the type where X is the anion of a mineral or saturated organic acid. a

It is essential that t e treating agents of this invention contain substantialiy only saturated alkyl groups since unsaturated groups, when present in substantial amounts,

greatly diminish or destroy entirely the ability of. the treating agents to modify and control the cour'se'of the reaction, and moreover, actually aggravate the troublesome frothing and foaming encountered in oresfwhich contain flotation agents. V

The manner of addition of the agent to the ore appears to be unimportant providing it is distributed in the reaction mixture prior to the actual reaction. The degree of distribution also is not critical and the ordinary mix-.

ing employed durin such digestion reactions appears to be sufiicient adequately to :distribute the agent through the reaction mass; The treating agent may, for example, be added to the ore at any convenient stage; prior to its introduction into the digestion vessel, or may be added ployed owing to partial .elir'ninationof the flotation agents during subsequent washing, drying," etcf, but the major portion of the organic agent usually remains associated V with the ore concentrate; Qwing to'the difiiculty of analyzing the ore concentrate for minute amounts of residual flotation agent and the utter 'irnpracticality of evaluating the reaction in commercial-scale equipment,-

which customarily involves reaction of from -10 to 20 tons of ore with from 15 to 30 tons of concentrated sulfuric acid for each batch, it has been found more practical and desirable to evaluate thereactive characteristics. of the ore and the quantity' of amine treatment agent re quired by means of an empirical; test which is carried out as follows: 3 a

V A 6"'i. d. cylindrical tank 14" high and having /4" steel walls and a ,3 steel plate bottom is provided with an iron sweep agitator having five sweeps,each 5 /27 X W and adjusted to operate at 200 RP. M. 1590 grams of theme to be tested are digested in this tank using the washed down with the remainderof the acid to be used;

'The amine treating agent is then added and finally the set-off'water, which has the dual function of diluting the same relative concentration of acid, the same relative acid to oreratio (based on 100% HzSOt) and the same relative quantity of set-oflf water as are to be employed,

in the full scale operation. This size charge, in the vessel just described, represents a straight scale model of a typical commercial reaction having approximately the same shape tankas a typical full-scale installation, and providing the same height freeboard, in proportion'to the charge employed. Approximately half of'the acid is first introduced'into the tank after. which the ore is'added and acid to properstrength forreaction and heating up the reaction mixture. The strongly exothermicreaction is' initiated and maintained by allowing a 'Meker burner to not so treated will be seen to foam violentlyand in many cases will overflow and project itself out of the reaction play' directly on the bottom of the tank throughout the j The course of the reaction is followed by visual observation and may :be recognized as com-' reaction cycle.

plete when copious evolutionof steam has taken place and subsided, followed by the setting-up of the reaction 'mixture to a rigid, porous cake, ordinarily from 15 to 20 minutes after the start of heating; When subjected to this test an ore which does not contain flotation agents will undergo avigorous but controlled reaction, and the reaction mass will ordinarily stay at least four inches below the top of the tank. An ore which contains flotation agents but is treated with theamine treating agents of this invention will behave in a substantially identical manner. .An ore which contains flotation agents and is tank} The effectiveness of the quantity of amine treating agent used is gauged by the height to which the reaction 7 mass rises in the tank, and the treatment isrconsidered completely effective if the highest point reached by the reaction mass is four or more inches below the top' of the tank. When suc'h is the case, the quantity oftreating agent "employedis suificient for thepurpose and the 'same relative amount of treating agents calculated on an ore weight basis may be employed safely in largescale operationsf The employment of the secondary amine treating agents of this invention apparently has no other observable efiect upon the course of the reaction than to offset the effect of the residual flotation agent; the reaction proceeds in substantially the same way as would be expected of a similar ore not containing flotation agents, and efliciencies and recoveries are likewise unimpaired. Addition of the amine treating agents of this invention to ores which do not contain flotation agents has no noticeable effect.

In order to more clearly illustrate the process of this invention, the following examples are presented:

Example I 1500 grams of a titaniferous iron concentrate which had been prepared by treating a titaniferous iron ore in a flotation system with 1.5 pounds of fuel oil and 1.0 pound of oleic acid per ton of the unconcentrated feed ore was tested according to the test method described above using 1370 milliliters of 93.2% sulfuric acid and 150 milliliters of water to give an acid strength at reaction of 88%. The reaction was extremely violent and a considerable portion of the reaction mass flowed over the top of the tank. The test was repeated using 0.05% of di octadecylamine, based on the weight of the ore. The reaction in this case Was moderately violent and the reaction mass rose to within about four inches from the top of the tank. The test was again repeated using 0.10% of di octadecylamine and the reaction was observed to be vigorous but completely controlled, the reaction mass in this case never rising higher than about five inches from the top of the tank.

On the basis of these preliminary tests, a large scale digestion was carried out using 10 tons of the same titaniferous iron ore concentrate, 16.8 tons of 93.2% sulfuric acid, pounds of di octadecylamine, and 1.1 tons of water. The reaction was rapid, complete and orderly, similar in all respects with reactions produced by ores not containing flotation agents. Better than 95% of the titanium values in the treated ore concentrate were convered to soluble titanium sulfates.

Example II Another ore concentrate was prepared by flotation concentration of a crude titaniferous ore using 1.0 pound of oleic acid and 1.5 pounds of fuel oil for each ton of raw ore treated. Approximately half of the original ore feed (together with most of the flotation agents) was collected as the flotation concentrate. After subsequent Washing and drying the flotation concentrate was tested as described in Example I using di octadecyl stearamide as the treating agent.

On the basis of the preliminary tests another large scale digestion was made according to the procedure described in Example I, but using 0.10% of di octadecyl stearamide as the treating agent. The character of the reaction obtained was substantially similar to that of Example I and resulted in the solubilization of better than 95% of the titanium values.

Example Ill An ore concentrate similar to that of Examples I and II was subjected to large scale digestion according to the procedure of Example I, using 0.05% of di hexadecyl ammonium stearate instead of the di octadecylamine as the secondary amine treating agent. Again, a vigorous orderly reaction took place resulting in solubilization of better than 95% of the titanium values.

Example IV Another ore concentrate similar to that of the preceding examples was subjected to large scale digestion according to the procedure of Example I, using 0.10% of di octadecyl ammonium palmitate instead of the di octadecylamine as the secondary amine treating agent. Results were substantially identical with those of Example I.

Example V Another portion of the ore concentrate used in Example IV was subjected to large scale digestion according to the procedure of Example I, using 0.10% of di octadecyl stearamide sulfate instead of the di octadecylamine as the secondary amine treating agent. Results were substantially identical with those of Example I. 7

Example VI Example VII A sample of ore taken from an ore pile which had been sprayed with asphalt to reduce wind losses was tested in the laboratory and was found to have serious foaming characteristics The amount of asphalt present in the ore was not known, but laboratory tests as previously described indicated that foaming at digestion could be prevented by the addition of 0.025% of di octadecylamine. This quantity was added to a plant-scale digestion batch, with results similar to those described in the previous examples.

As shown by the above examples, the present invention provides a method for treatment of ore concentrates containing organic flotation agents, which treatment renders said concentrates amenable to dissolution in strong sulfuric acid according to the normal procedures used for such concentrates. The ordinary effect associated with the presence of organic flotation agents in the ore is to render the reaction with sulfuric acid uncontrollable; by means of the present invention this harmful and dangerous effect of organic flotation agents is prevented and the digestion proceeds as readily and conveniently as when using ore which does not contain flotation agents. The treatment process is simple and easy to employ.

While this invention has been described and illustrated by the examples shown, it is not intended to be strictly limited thereto, and other modifications and variations may be employed within the scope of the following claims.

We claim:

1. A method for treatment of titaniferous ores containing organic flotation agents selected from the group consisting of anionic flotation agents, petroleum agents and asphalt materials to render the same amenable to attack by concentrated sulfuric acid which comprises adding to said ore from 0.05 to 0.2% of its weight of an amine having the formula wherein R and R represent saturated alkyl radicals containing from 12 to 20 carbon atoms and R is selected from the group consisting of hydrogen and saturated alkanoic acyl radicals containing up to about 20 carbon atoms.

2. In a method for dissolution in sulfuric acid of titaniferous ores containing organic flotation agents selected from the group consisting of anionic flotation agents, petroleum agents and asphalt materials, the improvement which comprises having present during said dissolution from 0.05 to 0.2%, based on the weight of said ore, of an amine, said amine having the formula wherein R and R represent saturated alkyl radicals condi octadecylamine;

taining from 12 to 20 carbon atoms and R is selected from the group consisting of hydrogen and saturated al anoic ,acyl radicals containing up to about-20 carbon atoms; I

3. A method of preparing titanium solutions relatively low in iron and gangue from crude ilm'enite'ore relatively high'in ironand gangue which comprises the stepsoi grinding said ore, concentrating the ihnenite portion of said ore by flotation in the presence of organic flotation agentsselected from the groupconsisting of anionic i flotation agents,"petro1eum agents and'asphalt materials, "thereby separating said crude ore into a floatable'fraction rich in ihnenite and a non-floatable fraction rich in gangue and 'low in titanium, and subsequently reacting said ilmenite richfraction with concentrated sulfuric acid in the presence ofan amine, said amine having the formula wherein R and R'lrepresent saturated'alkyl radicals containing from about '12 to 20 carbon atoms and R" is selected from the group consisting of hydrogen and saturated alkanoic acylradicals containingup to about 20 carbon atoms. 7 i 7 4. Method according to claim 1 wherein said amine is 1,

5. Method according to claim 1 wherein said is di hexadecyl ammonium stearate. 1

6. Method according to claim 1 wherein said amine 'di octadecyl steal-amide. u

7. Method according'to claim 1 wherein said amine is di octadecyl ammonium palmitate.

8. Method according to claim 1 wherein said amine is dioetadecyl ammonium myristate. r

9. A method for treatment of titaniferous ores'containing organic flotation agents selected 'from the group consisting 'ofanionic flotation agents, petroleum agents and asphalt 'niaterial t'o render said ores amenable to attack by concentrated sulfuric acid, which comprises,

adding tolsaid ore-from VOIOS to 0.2% of "its Weight of a substance selected from the group consistingfof amines having the formula V 7 References Cited in thefile of, this patent UNITED STATES PATENTS V Kingsbury Apr. 11', 1939 OTHER REFERENCES Taggart Handbook of Mineral Dressing, 2ndedition, I. Wiley andSons, N. Y.. 1945, pages 12-120, 12-123,

MacMurray: Froth flotation of ilmenite ore, pa'gc 339, vol. 173 of Transactions of American Institute of Mining and Metallurgical Engineers, N. Y; 1948. Lucas: Organic Chemistry, American Book Co.-,N. Y. 1935,- page 279. i i 

1. A METHOD FOR TREATMENT OF TITANIFEROUS ORES CONTAINING ORGANIC FLOTATION AGENTS SELECTED FROM THE GROUP CONSISTING OF ANIONIC FLOTATION AGENTS, PETROLEUM AGENTS AND ASPHALT MATERIALS TO RENDER THE SAME AMENABLE TO ATTACK BY CONCENTRATED SULFURIC ACID WHICH COMPRISES ADDING TO SAID ORE FROM 0.05 TO 0.2% OF ITS WEIGHT OF AN AMINE HAVING THE FORMULA 